The present application relates to a magnetic memory element having a layer structure including a plurality of perpendicular magnetization films which serve as a memory layer and a reference layer and which are stacked with a nonmagnetic material therebetween, and particularly to a structure of the reference layer.
In information devices such as computers, DRAMs (Dynamic Random Access Memories) with a high operation speed and a high density are widely used as RAMs (Radom Access Memories). However, DRAMs are volatile memories which lose information when power supplies are turned off, and thus nonvolatile memories which retain information are desired.
MRAMs (Magnetic Random Access Memories) which store information by magnetization of magnetic materials attract attention as a candidate of nonvolatile memories and are being developed.
Storage methods for MRAMs include a method of reversing magnetization by a current magnetic field, and a method of inducing magnetization reversal by injecting spin-polarized electrons directly into a memory layer as disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2004-193595. In particular, spin-injection magnetization reversal capable of decreasing a storage current with decrease in size of an element attracts attention.
Further, there is investigated a method using a perpendicular magnetization film composed of a magnetic material having a perpendicular magnetization direction in order to miniaturize an element as disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2009-81215.
A magnetic memory element has a layer structure including a memory layer and a reference layer serving as magnetic layers which are stacked with a nonmagnetic material therebetween.
As perpendicular magnetization films of a magnetic memory element having perpendicular magnetization, materials proposed for both the reference layer and the recording layer substantially are substantially the same and include TbFeCo, FePt, CoPt, Co/Pt continuous stacked films, and Co/Pd continuous stacked films.